Improvement in understanding of the optical properties of the human lens is essential to further improvement in both the design of opthalmoscopic lenses for examining the peripheral retina and the development of methods for determining the retinal loci of perimetric defects. We therefore propose: (1) to study the changes that occur in the refractive index distribution of the crystalline lens during the accommodation and aging, and to determine the dependence of those changes on the refractive state of the individual human eye, (2) to apply the results of (1) to increase our current understanding of the relationship between perimetric defects and their corresponding retinal pathology and to improve current methods for the design of both intraocular lenses and opthalmoscopic lenses for viewing the peripheral retina, (3) to develop superior clinical methods for localizing the retinal origin of functional (perimetric) visual losses through applications of the 90 degrees noncontact fundus camera and the high-resolution, flying-spot television opthalmoscope, and (4) to perform a careful clinical analyses of localizing methods developed for the 90 degrees noncontact camera both to improve those methods and to ensure their clinical practicability. Performance of these objectives would not only greatly improve clinical understanding of the functional consequences of vitreoretinal pathology, but also significantly increase understanding of (1) the opical consequences of presbyopia, (2) the relationship between phakic, aphakic and pseudophakic visual fields, and (3) the optimal design of intraocular lenses.